Multi-input multi-output (MIMO) refers to technology for improving transmission and reception efficiency of data by using multiple transmit antennas and multiple receive antennas instead of using one transmit antenna and one receive antenna. Upon using a single antenna, a receiving end receives data through a single antenna path. However, using multiple antennas, the receiving end receives data through multiple paths. Accordingly, use of multiple antennas can improve transmission rate and transmission throughput and increase coverage.
To raise multiplexing gain of a MIMO operation, a MIMO transmitting end may employ channel status information (CSI), which is fed back from a MIMO receiving end. The receiving end may determine the CSI by performing channel measurement using a prescribed reference signal (RS) received from the transmitting end.